Human monocyte activation by biologic and biodegradable meshes in vitro

Efficacy of Acellular Dermal Matrix Type in Treatment of Capsular Contracture in Breast Augmentation: A Systematic Review and Meta-Analysis

BACKGROUND

Capsular contracture is a known complication of breast augmentation and is among the top reasons for revisional breast augmentation procedures. The use of acellular dermal matrix (ADM) has been shown to reduce the rate of capsular contracture in breast reconstruction and augmentation, theorizing that it acts as a protective barrier between the implant capsule and inflammatory process responsible for capsular contracture. The role of ADM in treatment of capsular contracture has been investigated in numerous studies, with a variety of ADMs.

OBJECTIVES

The aim of this study was to perform a systematic review of existing literature on the use of ADM for treatment of capsular contracture in aesthetic breast augmentation patients to investigate differences in efficacy of ADM types.

METHODS

The PubMed, Embase, and CINAHL databases were systematically reviewed for articles pertaining to capsular contracture, acellular dermal matrices, and breast augmentation. Number of patients, type of ADM, Baker grade, follow-up time, complication rate, and capsular contracture rate were recorded from identified articles. Data was pooled from studies to calculate a capsular contracture rate for each ADM type, with a chi-squared test performed for analysis. Identified studies with a comparative group were included in a meta-analysis utilizing risk ratio (RR) to assess the efficacy of ADM.

RESULTS

Nine articles including ADM for treatment of capsular contracture in breast augmentation met criteria for inclusion, with a total of 481 breasts. Strattice was the most commonly utilized ADM (n = 391), followed by AlloDerm (n = 57). There was a statistically significant difference in efficacy of ADM among the studied ADM types (P < .001). AlloDerm, FlexHD, and DermaMatrix had the lowest capsular contracture rates (0%). NeoForm and SurgiMend had the highest capsular contracture rates (each 25%, but with n = 4 and n = 8, respectively). Strattice had a capsular contracture rate of 1.53% in the pooled data, and meta-analysis showed that Strattice reduced the risk of capsular contracture (RR 0.14 [95% CI 0.06, 0.31]) compared with conventional treatment.

CONCLUSIONS

Acellular dermal matrices appear to be effective at treating capsular contracture after breast augmentation while maintaining a low complication rate. Overall capsular contracture rates are low with the use of ADM. There is a statistically significant difference in efficacy among ADM types. Meta-analysis shows that Strattice is effective at reducing the risk of capsular contracture in breast augmentation patients when compared to conventional treatment. Future research, especially in the form of randomized controlled trials, is needed to further investigate the efficacy of various ADMs in the treatment of capsular contracture.

LEVEL OF EVIDENCE: 4

Early wound morbidity and clinical outcomes associated with P4HB mesh compared to permanent synthetic mesh in umbilical and small to medium, routine ventral hernia repairs

Background

Permanent synthetic meshes such as polypropylene (PP) have been utilized for hernia repair for decades, but concerns remain regarding potential long-term, mesh-related complications. A resorbable polymer such as poly-4-hydroxybutyrate (P4HB) represents an alternative with high initial strength, that gradually resorbs, leaving an abdominal wall that is at least as strong as it would be in its native state. We aimed to compare early wound morbidity and clinical outcomes associated with P4HB to traditional, permanent PP in umbilical and small to medium, routine ventral hernias using data from the Abdominal Core Health Quality Collaborative (ACHQC).

Methods

Inclusion criteria for the umbilical cohort included: all Centers for Disease Control and Prevention (CDC) wound classes, all Ventral Hernia Working Group (VHWG) hernia grades, and hernia defects <3 cm. The small to medium, routine ventral hernia cohort was limited to CDC class I wounds, VHWG hernia grades I and II, and hernia defects <5 cm. The study group was comprised of P4HB meshes; the comparator group was an aggregate of PP meshes. Clinical outcomes were assessed at 30 days.

Results

There was no significant difference in early wound morbidity, readmission, or reoperation between the P4HB and PP cohorts. A small number of patients experienced SSO, with ≤4% requiring procedural intervention. None of the patients (0% in all cases) experienced skin/soft tissue necrosis, infected seroma, infected hematoma, exposed/contaminated/infected mesh, enterocutaneous fistula, graft failure, or pain requiring intervention at 30-days. However, P4HB was associated with significantly greater operative time, length of stay, and use of myofascial release compared to PP (p < 0.05 in all cases).

Conclusions

Short-term clinical outcomes associated with resorbable P4HB mesh are comparable to permanent synthetic PP mesh in umbilical and small to medium, routine ventral hernia repairs, despite significant differences in operative time and length of stay. Longer-term follow-up is needed to expand on the clinical relevance of these short-term findings.

Biosynthetic meshes in contaminated fields: where are we now? A systematic review and meta-analysis in humans

PURPOSE

Selection of an appropriate mesh reinforcement for hernia repair in contaminated fields is a significant problem for surgeons. To date the proper mesh for contaminated fields has not been found. Biosynthetic meshes have emerged as new treatment option in contaminated fields. This study aims to evaluate the postoperative outcomes of biosynthetic meshes in contaminated fields.

METHODS

Systematic electronic search (PubMed, Medline, Embase, Scopus), according to PRISMA criteria, was performed. A literature search of scientific papers was performed by two reviewers until April 2021. Articles were chosen based on reference to biosynthetic meshes, their use in infected fields, and in human subjects. GRADE methodology and the modified Newcastle-Ottawa scale were used to assess the quality of studies. According to CDC-Centers for Disease Control classes patients were divided into two subgroups, group 1 (CDC class 2) and group 2 (CDC classes 3-4).

RESULTS

The research included 21 articles and 1619 patients were analyzed. Long-term follow-up showed a significant higher recurrence rate than short-term follow-up. P < 0.001. Meta-analysis of these studies showed that the SSI were significantly higher in CDC classes 3-4 than CDC class 2 (P < 0.01). No differences were found in SSO (P = 0.06) and recurrence (P = 0.37) rate among the two groups. Phasix™ was the most common mesh in 15 studies. The mean follow-up was 23.0 months. The surgical site infection (SSI) rate was 17.3%. The surgical site occurrence (SSO) rate was 32.4%. Recurrence rate was 11.5%.

CONCLUSION

This is the first systematic review and meta-analysis on the clinical outcomes of abdominal wall repair using biosynthetic mesh in contaminated-infected settings. The results show good results in patients at high risk of postoperative wound complications. The aim of this study is to add to the growing literature on biosynthetic mesh a picture of current literature evidence to help future researchers performing further studies on this topic.

A Feasibility and Safety Study of a Novel Human Decellularized Dermal Matrix to Accelerate Healing of Neuropathic Diabetic Foot Ulcers in People With Type 1 and Type 2 Diabetes

OBJECTIVES

The purpose of this study was to determine the feasibility and safety of a novel decellularized dermal matrix (DDM) for the treatment of chronic diabetic foot ulcers (DFUs).

METHODS

An interventional, single-arm, prospective study of DDM for DFU treatment was conducted in 2 Canadian centres from July 1, 2016, to May 30, 2017. Individuals ≥18 years of age with an active DFU of ≥2 weeks and ulcer area ≥1 cm2 before debridement and who consented to participate were enrolled in this clinical trial.

RESULTS

A total of 11 patients were enrolled, with 9 patients (82%) having achieved 100% closure between 2 and 8 weeks. The mean and median times to wound closure for these patients were 3.3 and 2.5 weeks, respectively. The mean and median reductions in wound area at 4 weeks posttreatment were 87% and 100%, respectively. The proportion of patients having achieved complete healing at 12 weeks was 82%. All patients received only 1 DDM application to achieve these results. There were no adverse events related to use of the product. No cases of recurrence during a 1-year follow-up after completion of the study were reported for patients who achieved wound closure.

CONCLUSIONS

These findings provide evidence that this DDM may be safe and effective for the treatment of chronic, hard-to-heal neuropathic DFUs. Specifically, DDM demonstrated the potential to accelerate healing of DFUs when compared with reported times of 8 to 12 weeks required to achieve closure using the current standard of care.

Submuscular Implant-Based Breast Reconstruction Using a Musculofascial Pocket Formed by the Pectoralis Major Muscle and the Serratus Anterior Muscle Fascia: A Novel Surgical Approach

BACKGROUND

Subpectoral implant-based breast reconstruction following mastectomy commonly severs the inferior border of the pectoralis major muscle for better projection of the lower pole. This can affect a patient's postoperative motor function and result in animation deformity. Implant-based breast reconstruction using partial muscle coverage with an acellular dermal matrix (ADM) can be costly. There is an unmet clinical need for a novel surgical method for submuscular implant-based breast reconstruction.

METHODS

We describe an innovative technique for submuscular implant-based breast reconstruction following mastectomy. The approach utilizes the serratus anterior muscle fascia connected to the lateral margin of the pectoralis major muscle to form a lateral tissue pocket for implant coverage. This method preserves the inferior border of the pectoralis major muscle and minimizes the size of ADM coverage. Patient satisfaction on the BREAST-Q Reconstruction Module and complications were assessed 12 months after surgery.

RESULTS

The novel surgical design was safe and used minimal ADM (6 × 5cm²). Mean satisfaction with breasts was 61 ± 4.7 (range, 48-73), mean psychosocial well-being was 66 ± 10 (range, 50-93), and mean sexual well-being was 47 ± 7.8 (range, 27-70). Animation deformity was avoided by preserving the inferior border of the pectoralis major muscle. Rates of revision (7.6%) and postsurgical seroma (3.4%) were low, and capsular contracture was minimal.

CONCLUSIONS

Submuscular implant-based breast reconstruction following mastectomy utilizing the serratus anterior muscle fascia connected to the lateral margin of the pectoralis major muscle to form a lateral tissue pocket for implant coverage is safe, feasible, and generates good aesthetic outcomes.

Postoperative Complications in Breast Reconstruction With Porcine Acellular Dermis and Polypropylene Meshes in Subpectoral Implant Placement

AIM

This research compares postoperative complication rates with Strattice™, SERAGYN^® BR, and TiLOOP^® Bra interposition devices for subpectoral implant placement after skin or nipple sparing mastectomy.

PATIENTS AND METHODS

188 breast reconstructions in 157 patients after primary (n=96), secondary (n=71), or prophylactic (n=21) surgery were analyzed regarding major and minor complications.

RESULTS

With acellular dermal matrix (ADM) Strattice™, 27.5% major and 27.5% minor complications occurred. Implant loss rates were 27.3% in primary and 30.8% in secondary reconstructions. With SERAGYN^® BR, 11.1% major and 13,0% minor complications occurred. Implant losses (6.1%) occurred exclusively in primary reconstructions. With TiLOOP^® Bra, 14.9% major and 9.6% minor complications occurred. Implant loss rates were 7.7% in primary and 7.1% in secondary reconstructions.

CONCLUSION

ADM was associated with high complication rates in primary and secondary reconstructions. Low complication rates were seen with mesh interposition devices in primary, secondary, and prophylactic reconstructions.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Human Primary Dermal Fibroblasts Interacting with 3-Dimensional Matrices for Surgical Application Show Specific Growth and Gene Expression Programs

Several types of 3-dimensional (3D) biological matrices are employed for clinical and surgical applications, but few indications are available to guide surgeons in the choice among these materials. Here we compare the in vitro growth of human primary fibroblasts on different biological matrices commonly used for clinical and surgical applications and the activation of specific molecular pathways over 30 days of growth. Morphological analyses by Scanning Electron Microscopy and proliferation curves showed that fibroblasts have different ability to attach and proliferate on the different biological matrices. They activated similar gene expression programs, reducing the expression of collagen genes and myofibroblast differentiation markers compared to fibroblasts grown in 2D. However, differences among 3D matrices were observed in the expression of specific metalloproteinases and interleukin-6. Indeed, cell proliferation and expression of matrix degrading enzymes occur in the initial steps of interaction between fibroblast and the investigated meshes, whereas collagen and interleukin-6 expression appear to start later. The data reported here highlight features of fibroblasts grown on different 3D biological matrices and warrant further studies to understand how these findings may be used to help the clinicians choose the correct material for specific applications.

Efficacy of Acellular Dermal Matrix in Capsular Contracture of Implant-Based Breast Reconstruction: A Single-Arm Meta-analysis

BACKGROUND

A large number of clinical studies have suggested that acellular dermal matrix (ADM) can decrease the incidence of capsular contracture in implant-based breast reconstruction. Yet, there is currently no high-level epidemiological evidence to prove this. The goal of this meta-analysis was to clarify the efficacy of ADM in capsular contracture, and provide a reference value for plastic surgeons.

METHODS

We systematically performed a search on PubMed, EMBASE, and the Cochrane Library to identify eligible studies from inception up to October 1, 2019. A random-effects model was used to obtain a pooled incidence rate. We conducted subgroup analysis according to geographic region, type of ADM, body mass index (BMI), duration of follow-up, and proportion of participants who have received radiotherapy.

RESULTS

A total of 18 studies involving 2941 cases were included. Overall, the pooled incidence rate of capsular contracture was 2.4% (95% CI 1.2-3.9%). The results from subgroup analyses indicated an even lower incidence in North America (1.6%, 95% CI 0.5-3.3%) and in human-derived ADM (HADM) (1.2%, 95% CI 0.2-3.0%). In addition, the results showed that the patients with BMI < 24, or who have received radiotherapy, were more prone to capsular contracture.

CONCLUSION

The application of ADM can effectively reduce the incidence of capsular contracture in implant-based breast reconstruction. And we infer that it might also apply to breast augmentation. However, additional high-quality trials are warranted to corroborate the findings of this meta-analysis.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Regulation of Peritoneal Inflammatory Response to Implant Material Using an Ex Vivo Model System

BACKGROUND

Implants used in abdominal wall reconstruction are associated with intra-abdominal inflammation that can cause complications such as adhesions, fistulae, or failure of the implant. This study analyzed the inflammatory response of human peritoneum explants when exposed to different implant materials including synthetic and biological (cross-linked and non-cross-linked).

MATERIALS AND METHODS

Human peritoneum explants (parietal and visceral) were incubated in culture with implants used for abdominal wall reconstruction. Implants included Permacol (biological implant with chemical cross-linking); Biodesign and Strattice (biological implants without chemical cross-linking); Prolene (synthetic nonabsorbable); and Vicryl (synthetic absorbable). Control peritoneum samples were incubated without implant. Cytokine concentrations and corresponding gene expression were measured by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. Further evaluation included assessment of tissue viability and implant-cytokine adsorption.

RESULTS

Incubation of human peritoneal explants with Biodesign or Strattice was associated with a significant reduction in interleukin-6, interleukin-1β, and tumour necrosis factor alpha protein and gene expression compared with control. These could not be explained by reduced cell viability or implant-cytokine adsorption. Incubation of explants in Biodesign-conditioned media displayed a similar effect to incubation of explants with Biodesign itself.

CONCLUSIONS

Human peritoneal explants cultured with different mesh implant materials show an altered inflammatory cytokine response suggesting a tissue-specific response. Downregulation of key inflammatory cytokines by the peritoneum exposed to non-cross-linked biological implants may be mediated by the release of soluble factors from these implants inhibiting cytokine gene expression. This ex vivo human peritoneal system provides a novel preclinical model to investigate peritoneum-implant interactions.

Evidence for the Use of Acellular Dermal Matrix in Implant-Based Breast Reconstruction

Acellular dermal matrices (ADMs) are tissue grafts that have been specially processed to remove all cellular components. These machined biological scaffolds have become popular in a variety of surgical settings due to their rapid incorporation into living tissue. As ADMs are highly malleable and cause minimal inflammation, they have come to serve as a useful tool in implant-based breast reconstruction procedures. The major benefits of using an ADM in this setting include superior initial breast contouring, decreased risk of capsular contracture after implant insertion, and consistent sustained positioning of the reconstructed breast. Despite these advantages, these tissue grafts are foreign to the host, and postoperative complications following ADM insertion, including infection and seroma, have been well documented. When considering using ADMs in this setting, it is important to first consider patient-specific factors that could preclude their use, such as low body mass index, small breasts, or a history of radiation exposure to the breast tissue. ADM grafts are also expensive, which may present another barrier to their use. Review of the literature ultimately suggests a continued role for ADMs in implant-based breast reconstruction, and continued research in this field is warranted.

Biologic meshes and synthetic meshes in cancer patients: a double-edged sword: differences in production of IL-6 and IL-12 caused by acellular dermal matrices in human immune cells

PURPOSE

In 2005, Breuing et al. first described the use of acellular dermal matrices (ADMs) in breast cancer patients. ADMs are assumed to be safe to use in an oncologic setting, but data from controlled studies are still needed. Here, we investigate the effects of ADMs on the production of interleukin (IL)-6 and IL-12, key regulators of immune suppression and activation.

METHODS

Strattice (ST), CollaMend (CM), and Biodesign (BD) biologic meshes and TiLoop, a synthetic mesh (TL), were used in this study. We isolated myeloid dendritic cells (MDCs), untouched plasmacytoid dendritic cells (pDCs), naïve B cells, and CD8+ T cells and co-cultured these cells with either the biologic meshes or TL. As positive controls, we used CpG ODN 2216 or lipopolysaccharide (LPS). The cytokine concentrations of IL-12p70 and IL-6 were determined after 7 days using sandwich ELISA sets.

RESULTS

There were highly significant differences between the ADMs and TL in terms of their ability to stimulate immunologic responses. IL-6 expression was significantly increased in B cells (p = 0.0006131) and T cells (p = 0.00418) when comparing TL and ADMs. We also identified significant differences in IL-12 production by B cells (p = 0.0166) and T cells (p = 0.003636) when comparing TL and ADMs.

CONCLUSIONS

Despite the assumed lack of an immunological response to ADMs, in our experimental study, human immune cells reacted with significantly different cytokine profiles. These findings may have implications for the potential activation or suppression of effector cells in cancer patients and could explain some of the post clinical post surgical signs of ADMS like skin rush and seroma.

Early Wound Morbidity after Open Ventral Hernia Repair with Biosynthetic or Polypropylene Mesh

BACKGROUND

Recently introduced slow-resorbing biosynthetic and non-resorbing macroporous polypropylene meshes are being used in hernias with clean-contaminated and contaminated wounds. However, information about the use of biosynthetic meshes and their outcomes compared with polypropylene meshes in clean-contaminated and contaminated cases is lacking. Here we evaluate the use of biosynthetic mesh and polypropylene mesh in elective open ventral hernia repair (OVHR) and investigate differences in early wound morbidity after OVHR within clean-contaminated and contaminated cases.

STUDY DESIGN

All elective, OVHR with biosynthetic mesh or uncoated polypropylene mesh from January 2013 through October 2016 were identified within the Americas Hernia Society Quality Collaborative. Association of mesh type with 30-day wound events in clean-contaminated or contaminated wounds was investigated using a 1:3 propensity-matched analysis.

RESULTS

Biosynthetic meshes were used in 8.5% (175 of 2,051) of elective OVHR, with the majority (57.1%) used in low-risk or comorbid clean cases. Propensity-matched analysis in clean-contaminated and contaminated cases showed no significant difference between biosynthetic mesh and polypropylene mesh groups for 30-day surgical site occurrences (20.7% vs 16.7%; p = 0.49) or unplanned readmission (13.8% vs 9.8%; p = 0.4). However, surgical site infections (22.4% vs 10.9%; p = 0.03), surgical site occurrences requiring procedural intervention (24.1% vs 13.2%; p = 0.049), and reoperation rates (13.8% vs 4.0%; p = 0.009) were significantly higher in the biosynthetic group.

CONCLUSIONS

Biosynthetic mesh appears to have higher rates of 30-day wound morbidity compared with polypropylene mesh in elective OVHR with clean-contaminated or contaminated wounds. Additional post-market analysis is needed to provide evidence defining best mesh choices, location, and surgical technique for repairing contaminated ventral hernias.

Muscle-Sparing ADM-Assisted Breast Reconstruction Technique Using Complete Breast Implant Coverage: A Dual-Institute UK-Based Experience

BACKGROUND

We report our early experience of a novel muscle-sparing breast (prepectoral) reconstruction technique using a pre-shaped Braxon® mesh (acellular dermal matrix) which completely wraps around the breast implant.

METHODS

All patients who underwent prepectoral implant-based breast reconstruction between April 2014 and September 2015 were included in the analysis. The dermal matrix Braxon® used is a pre-shaped matrix which forms a complete implant mesh wrap. The new breast created is placed over the chest wall without disturbing the pectoralis musculature.

RESULTS

A total of 51 (42 unilateral and 9 bilateral) muscle-sparing breast reconstructions were carried out. Complications included implant loss (n = 1; 1.7%) secondary to wound infection, seroma (n = 4; 6.7%), and superficial wound dehiscence (n = 1; 1.7%) which was re-sutured without further complication. The median follow-up period was 16.4 (range 8-25) months.

CONCLUSION

The early experience appears highly satisfactory with good clinical outcome. The novel prepectoral implant-based breast reconstruction using the mesh wrap provides an effective alternative to the more traditional submuscular implant-based technique.

The host response to naturally-derived extracellular matrix biomaterials

Biomaterials based on natural materials including decellularized tissues and tissue-derived hydrogels are becoming more widely used for clinical applications. Because of their native composition and structure, these biomaterials induce a distinct form of the foreign body response that differs from that of non-native biomaterials. Differences include direct interactions with cells via preserved moieties as well as the ability to undergo remodeling. Moreover, these biomaterials could elicit adaptive immune responses due to the presence of modified native molecules. Therefore, these biomaterials present unique challenges in terms of understanding the progression of the foreign body response. This review covers this response to natural materials including natural polymers, decellularized tissues, cell-derived matrix, tissue derived hydrogels, and biohybrid materials. With the expansion of the fields of regenerative medicine and tissue engineering, the current repertoire of biomaterials has also expanded and requires continuous investigation of the responses they elicit.

Design Strategies and Applications of Biomaterials and Devices for Hernia Repair

Hernia repair is one of the most commonly performed surgical procedures worldwide, with a multi-billion dollar global market. Implant design remains a critical challenge for the successful repair and prevention of recurrent hernias, and despite significant progress, there is no ideal mesh for every surgery. This review summarizes the evolution of prostheses design toward successful hernia repair beginning with a description of the anatomy of the disease and the classifications of hernias. Next, the major milestones in implant design are discussed. Commonly encountered complications and strategies to minimize these adverse effects are described, followed by a thorough description of the implant characteristics necessary for successful repair. Finally, available implants are categorized and their advantages and limitations elucidated, including non-absorbable and absorbable (synthetic and biologically derived) prostheses, composite prostheses, and coated prostheses. This review not only summarizes the state of the art in hernia repair, but also suggests future research directions toward improved hernia repair utilizing novel materials and fabrication methods.

Use of human acellular dermal matrix during classic bladder exstrophy repair

INTRODUCTION

The extent of the abdominal wall defect in people with classic bladder exstrophy (CBE) varies, and can be extensive. In this study, human acellular dermis (HAD) was used to bridge the fascial gap, as an alternative to osteotomy, to support a fascial repair of the abdominal wall, and as a filler in selected cases of CBE.

OBJECTIVE

To demonstrate the efficacy of the employed techniques of using HAD within the bladder exstrophy population.

MATERIALS AND METHODS

The medical records of six males, born with CBE, and who had abdominal wall defects were reviewed. Two children, aged 6 and 8 years old, were referred from overseas with unrepaired bladder exstrophy plates and large abdominal wall defects (8 cm and 12 cm wide). Both had their bladders reconstructed, placed within the pelvis, and HAD was used to replace the absent abdominal wall (bridged repair) without the use of pelvic osteotomy. In three other patients, HAD reinforced the native fascial repair (bolster repair). In three patients, HAD also served as a filler for the abdominal depression that was present following initial staged repair. Where HAD was used for bridged or bolster repair, the edges of the allograft were extended 2-3 cm circumferentially beyond the perimeter of the abdominal wall defect.

RESULTS

All six patients healed well, without evidence of abdominal wall hernias at 1-3 years postoperatively. Functionally, each patient regained an appropriate level of abdominal wall strength. Two children successfully underwent a secondary procedure through the bridged allograft repair, as each required bladder neck reconstruction and bilateral ureteral reimplantation through the reconstructed abdominal wall. Continence was achieved in these two patients, with one child voiding at 2-hourly intervals and the second at 3-hourly intervals. One patient developed a urethral-cutaneous fistula, distant to location of the allograft. There were no associated wound complications.

CONCLUSIONS

In this series of patients born with classic bladder exstrophy, HAD acted as a biologic scaffold and allowed native cellular ingrowth and tissue remodeling. It served as an alternative to pelvic osteotomy in older patients with unrepaired CBE. The material reinforced a weak or potentially suboptimal fascial repair and filled a tissue gap, resulting in improved aesthetics. Given its ease of preparation and the lack of significant morbidity associated with its use, combined with the functional and esthetic results in the present series, HAD may be considered during delayed reconstruction of abdominopelvic tissues in people born with CBE.

Comparison of AlloDerm and AlloMax tissue incorporation in rats

BACKGROUND

Human acellular dermal matrices (HADMs) are used in a variety of settings. AlloMax is a new HADM currently being used for breast reconstruction and hernia repair. We compared the in vivo tissue integration of AlloMax to AlloDerm, a well-studied HADM, in rats.

METHODS

We implanted AlloDerm and AlloMax patches into subcutaneous pockets on the backs of 32 male Sprague-Dawley rats. The animals were killed after either 4 or 8 weeks, and the patches were recovered and stained for histopathologic analyses. Microscopic end points included patch thickness, vascularization, tissue in-growth, fibroblast proliferation, and inflammation.

RESULTS

All animals completed the study without complications or infection. There were no significant differences in graft thicknesses at 4 and 8 weeks. Microscopically, at 4 weeks, AlloDerm sections had significantly more microvessels than AlloMax (P = 0.02). This disparity increased by 8 weeks (P < 0.01). Similarly, we found greater tissue in-growth and fibroblast proliferation in AlloDerm than AlloMax sections at 4 (P < 0.01) and at 8 (P < 0.01) weeks. Inflammatory infiltrates consisted of lymphocytes, histiocytes, eosinophils, and plasma cells. Deep graft infiltration by predominately lymphocytic inflammatory cells was significantly higher in AlloDerm than AlloMax grafts at 4 (P = 0.01) and 8 (P = 0.02) weeks. Graft necrosis was uncommon, but marginal fibrosis was similar in both.

CONCLUSIONS

AlloDerm grafts had greater neovascularization, tissue infiltration, fibroblast proliferation, and inflammatory reaction than AlloMax grafts when placed subcutaneously in rats. AlloDerm may be better incorporated than AlloMax when placed in vivo.

Non-cross-linked porcine acellular dermal matrix (Strattice Tissue Matrix) in pediatric reconstructive surgery

BACKGROUND

A variety of prosthetic materials are used in the pediatric population for abdominal and chest wall reconstruction. Pediatric experience of non-cross-linked porcine acellular dermal matrix is limited to patients following liver transplantation. We review our outcomes in patients in whom this matrix was used.

METHODS

A retrospective analysis of patients who underwent abdominal and chest wall reconstruction with a non-cross-linked porcine acellular dermal matrix (Strattice TM) was performed to assess clinical outcomes.

RESULTS

The tissue matrix was used in thirteen patients over a three-year period. Eleven had abdominal wall reconstruction and two underwent chest wall reconstruction. Seven procedures were contaminated at the time of surgery. Median age at insertion was 8.1years (5days-18years) with a median weight of 20.6kg (1.9kg-99kg). The tissue matrix failed in one patient with no unanticipated adverse events.

CONCLUSION

Future growth and need for reoperation requires special consideration in pediatric patients undergoing abdominal or thoracic wall reconstruction. Non-cross-linked porcine acellular dermal matrix can be safely used for abdominal and chest wall reconstruction in the pediatric population with a number of advantages over previously utilized materials. In our study, children have a favorable risk profile as compared to published adult series.

Fabrication of silk mesh with enhanced cytocompatibility: preliminary in vitro investigation toward cell-based therapy for hernia repair

Recent studies have demonstrated that combining cells with meshes prior to implantation successfully enhanced hernia repair. The idea is to create a biologic coating surrounding the mesh with autologous cells, before transplantation into the patient. However, due to the lack of a prompt and robust cell adhesion to the meshes, extensive in vitro cultivation is required to obtain a homogenous cell layer covering the mesh. In this context, the objective of this publication is to manufacture meshes made of silk fibres and to enhance the cytoadhesion and cytocompatibility of the biomaterial by surface immobilization of a pro-adhesive wheat germ agglutinin (lectin WGA). We first investigated the affinity between the glycoprotein WGA and cells, in solution and then after covalent immobilization of WGA on silk films. Then, we manufactured meshes made of silk fibres, tailored them with WGA grafting and finally evaluated the cytocompatibility and the inflammatory response of silk and silk-lectin meshes compared to common polypropylene mesh, using fibroblasts and peripheral blood mononuclear cells, respectively. The in vitro experiments revealed that the cytocompatibility of silk can be enhanced by surface immobilization with lectin WGA without exhibiting negative response in terms of pro-inflammatory reaction. Grafting lectin to silk meshes could bring advantages to facilitate cell-coating of meshes prior to implantation, which is an imperative prerequisite for abdominal wall tissue regeneration using cell-based therapy.

The Effect of Biomaterials Used for Tissue Regeneration Purposes on Polarization of Macrophages

Activation of macrophages is critical in the acute phase of wound healing after implantation of surgical biomaterials. To understand the response of macrophages, they are often cultured in vitro on biomaterials. Since a wide range of biomaterials is currently used in the clinics, we undertook a systematic review of the macrophage polarization in response to these different surgical biomaterials in vitro. Beside the chemistry, material characteristics such as dimension, pore size, and surface topography are of great influence on the response of macrophages. The macrophage response also appears to depend on the differences in sterilization techniques that induce lasting biochemical changes or residues of chemicals and their byproducts used for sterilization. Regarding tissue-based biomaterials, macrophages on human or porcine dermis, strongly cross-linked by chemicals elicit in general a proinflammatory response with higher amounts of proinflammatory cytokines. Synthetic biomaterials such as polyethylene, polyethylene terephthalate (PET) + polyacrylamide (PAAm), PET + sodium salt of poly(acrylic acid) (PAANa), perfluoropolyether (PFPE) with large posts, PEG-g-PA, and polydioxanone (PDO) always appear to elicit an anti-inflammatory response in macrophages, irrespective of origin of the macrophages, for example, buffy coats or full blood. In conclusion, in general in vitro models contribute to evaluate the foreign body reaction on surgical biomaterials. Although it is difficult to simulate complexity of host response elicited by biomaterials, after their surgical implantation, an in vitro model gives indications of the initial foreign body response and allows the comparison of this response between biomaterials.

Use of Acellular Dermal Matrix in Postmastectomy Breast Reconstruction: Are All Acellular Dermal Matrices Created Equal?

BACKGROUND

AlloDerm and FlexHD are two types of acellular dermal matrices commonly used in implant-based reconstruction. Although the use of acellular dermal matrix has revolutionized immediate breast reconstruction in the setting of breast cancer, it remains unclear which type of acellular dermal matrix is best. The purpose of this retrospective cohort study was to compare postoperative complication rates between these two types of acellular dermal matrix.

METHODS

The authors reviewed the records of all patients who underwent implant-based breast reconstruction at their institution between 1998 and 2013. Dependent variables of seroma, hematoma, infection, delayed wound healing, implant exposure, and return to the operating room for management of complications were recorded.

RESULTS

A total of 309 consecutive patients were identified. Of these, AlloDerm was used in 123 patients (39.8 percent) and FlexHD was used in 186 patients (60.2 percent). Most patients in the authors' cohort underwent immediate reconstruction [n = 288 (93.2 percent)], with a mean follow-up of 20.0 months. Patients receiving AlloDerm were half as likely to have major infections compared with patients receiving FlexHD (OR, 0.50; 95 percent CI, 0.16 to 1.00; p < 0.05). The rates of other complications were similar between the two groups.

CONCLUSION

There are significantly increased odds of a major infection in patients who undergo implant-based breast reconstruction using FlexHD compared with AlloDerm.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Capsular Contracture in Implant-Based Breast Reconstruction: Examining the Role of Acellular Dermal Matrix Fenestrations

BACKGROUND

Acellular dermal matrices have been proposed to decrease the incidence of capsular contracture in implant-based breast reconstructions. The authors have modified acellular dermal matrices with fenestrations to facilitate greater lower pole expansion and improve contour. The effect of fenestrations on the ability of matrices to suppress capsule formation, however, has not been examined.

METHODS

A retrospective review of all fenestrated acellular dermal matrix-assisted, implant-based breast reconstructions performed by the two senior authors, with a minimum of 1-year follow-up after permanent implant placement, was completed. Patient demographics, details of extirpative and reconstructive procedures, and complications were examined. Capsular contractures were scored according to the Baker grading scale and compared to those reported in the literature.

RESULTS

Thirty patients (50 breasts) underwent fenestrated acellular dermal matrix-assisted reconstruction, with mean follow-up times of 3.3 and 2.6 years after expander placement and implant exchange, respectively. Seven patients (23 percent) had a body mass index greater than 30 kg/m, three (10 percent) were active smokers, and six breasts (12 percent) were irradiated. Complications included one infection (2 percent), six cases (12 percent) of incisional superficial skin necrosis, and one (2 percent) tissue expander extrusion. Zero breasts had clinically significant Baker grade III/IV capsular contracture. The average Baker grade was 1.1.

CONCLUSIONS

Fenestrated acellular dermal matrices decrease capsular contracture to rates similar to what is seen with nonfenestrated matrices. Further research is necessary to determine whether this observation is a result of decreased need for inferolateral acellular dermal matrix coverage to achieve these effects or modified physical interaction of acellular dermal matrices with surrounding soft tissues.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Remodeling of Noncrosslinked Acellular Dermal Matrices in a Rabbit Model of Ventral Hernia Repair

Background: Bioprostheses represent a significant advance in the abdominal wall reconstruction since they become degraded until their complete elimination in the recipient organism. This study examines remodeling in the host of three noncrosslinked porcine dermal collagen biomeshes: Strattice™ (St; LifeCell Corp.), XCM Biologic® Tissue Matrix (XCM; Synthes CMF) and Protexa® (Pr; Deco Med S.R.L.). Methods: Partial ventral hernia defects created in New Zealand White rabbits were repaired using the biomeshes that were placed in an inlay, preperitoneal position. At 14 and 90 days after implantation, explants were assessed in terms of their host tissue incorporation by morphological studies, collagen gene/protein expression (quantitative real-time PCR/immunofluorescence), macrophage response (immunohistochemistry) and biomechanical strength. Results: There were no cases of mortality or infection. Among our macroscopic findings, the mesh detachment detected in one third of the Pr implants at 90 days was of note. The host tissue response to all the biomeshes was similar at both time points, with a tendency observed for their encapsulation. There were no appreciable signs of mesh degradation. The extent of host tissue infiltration and collagenization was greater for St and Pr than for XCM. Macrophages were observed in zones of inflammation and tissue infiltration inside the mesh. XCM showed a greater macrophage response at 90 days (p < 0.05). Improved tensile strength was observed for St (p < 0.05) over Pr and unrepaired defects. Conclusions:St showed the best behavior, featuring good collagenization and tensile strength while also inducing a minimal foreign body reaction.

Decreased hernia recurrence using autologous platelet-rich plasma (PRP) with Strattice™ mesh in a rodent ventral hernia model

BACKGROUND

Recurrence after ventral hernia repair (VHR) remains a multifactorial problem still plaguing surgeons today. Some of the many contributing factors include mechanical strain, poor tissue-mesh integration, and degradation of matrices. The high recurrence rate witnessed with the use of acellular dermal matrices (ADM) for definitive hernia repair has reduced their use largely to bridging repair and breast reconstruction. Modalities that improve classic cellular metrics of successful VHR could theoretically result in improved rates of hernia recurrence; autologous platelet-rich plasma (PRP) may represent one such tool, but has been underinvestigated for this purpose.

METHODS

Lewis rats (32) had chronic ventral hernias created surgically and then repaired with Strattice™ mesh alone (control) or mesh + autologous PRP. Samples were harvested at 3 and 6 months postoperatively and compared for gross, histologic, and molecular outcomes of: neovascularization, tissue incorporation, peritoneal adhesions, hernia recurrence, and residual mesh thickness.

RESULTS

Compared to control at 3 months postoperatively, PRP-treated rats displayed significantly more neovascularization of implanted mesh and considerable upregulation of both angiogenic genes (vEGF 2.73-fold, vWF 2.21-fold) and myofibroblastic genes (αSMA 9.68-fold, FSP-1 3.61-fold, Col1a1 3.32-fold, Col31a1 3.29-fold). Histologically, they also showed enhanced tissue deposition/ingrowth and diminished chronic immune cell infiltration. Peritoneal adhesions were less severe at both 3 (1.88 vs. 2.94) and 6 months (1.63 vs. 2.75) by Modified Hopkins Adhesion Scoring. PRP-treated rats experienced decreased hernia recurrence at 6 months (0/10 vs. 7/10) and had significantly improved ADM preservation as evidenced by quantification of residual mesh thickness.

CONCLUSIONS

PRP is an autologous source of pro-regenerative growth factors and chemokines uniquely suited to soft tissue wound healing. When applied to a model of chronic VHR, it incites enhanced angiogenesis, myofibroblast recruitment and tissue ingrowth, ADM preservation, less severe peritoneal adhesions, and diminished hernia recurrence. We advocate further investigation regarding PRP augmentation of human VHR.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.

Biologic versus Synthetic Mesh Reinforcement: What are the Pros and Cons?

Preserving patients' native tissues has posed many challenges for surgeons. Increased life expectancy is leading to a proportionately older surgical population with weaker tissues. The growing population of morbidly obese patients in addition to those with multiple comorbidities which influence the native strength and perfusion of tissues compounds the surgeon's challenge. Certainly, there is a rising demand for materials to replace or augment a patient's native tissue when it has been compromised. Over time, the number of products available has increased substantially. The ideal substitute, however, is debatable. The manufacturing and processing of these materials has become more complex and this has resulted in a significant increase in cost. The composition of the mesh, clinical scenario, and operative technique all interact to impact the long-term results. Surgeons require a thorough understanding of these products to guide proper selection and use, to ensure optimal outcomes for patients, and to properly steward financial resources. This review will outline the properties of commonly used materials, highlighting the strength and weakness of each. It will then discuss recommendations regarding mesh selection, coding, and reimbursement. While general principles and trends can be highlighted, further studies of biologic versus synthetic meshes are clearly necessary.

Anti-endotoxic and antibacterial effects of a dermal substitute coated with host defense peptides

Biomaterials used during surgery and wound treatment are of increasing importance in modern medical care. In the present study we set out to evaluate the addition of thrombin-derived host defense peptides to human acellular dermis (hAD, i.e. epiflex(®)). Antimicrobial activity of the functionalized hAD was demonstrated using radial diffusion and viable count assays against Gram-negative Escherichia coli, Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. Electron microscopy analyses showed that peptide-mediated bacterial killing led to reduced hAD degradation. Furthermore, peptide-functionalized hAD displayed endotoxin-binding activity in vitro, as evidenced by inhibition of NF-κB activation in human monocytic cells (THP-1 cells) and a reduction of pro-inflammatory cytokine production in whole blood in response to lipopolysaccharide stimulation. The dermal substitute retained its anti-endotoxic activity after washing, compatible with results showing that the hAD bound a significant amount of peptide. Furthermore, bacteria-induced contact activation was inhibited by peptide addition to the hAD. E. coli infected hAD, alone, or after treatment with the antiseptic substance polyhexamethylenebiguanide (PHMB), yielded NF-κB activation in THP-1 cells. The activation was abrogated by peptide addition. Thus, thrombin-derived HDPs should be of interest in the further development of new biomaterials with combined antimicrobial and anti-endotoxic functions for use in surgery and wound treatment.

Effects of mesenchymal stem cell and fibroblast coating on immunogenic potential of prosthetic meshes in vitro

BACKGROUND

The aim of this study was to reveal the effect of fibroblast or mesenchymal stem cell (MSC) coating on the mesh-induced production of IL-1β, IL-6, and VEGF by macrophages.

METHODS

Four commonly used surgical meshes were tested in this study, including Parietex, SoftMesh, TIGR, and Strattice. One-square-centimeter pieces of each mesh were placed on top of a monolayer of human fibroblasts or rat MSCs. The coating status was monitored with a light microscope. The human promonocytic cell line U937 was induced to differentiate into macrophages (MΦ). Three weeks later, meshes were transferred to new 24-well plates and cocultured with the MΦs for 72 h. Culture medium was collected and analyzed for IL-1β, IL-6, and VEGF production using standard ELISA essays. Parallel mesh samples were fixed with paraformaldehyde or glutaraldehyde for histology or transmission electronic microscopy (TEM) analyses, respectively.

RESULTS

Uncoated meshes induced increased production of all three cytokines compared with macrophages cultured alone. HF coating further increased the production of both IL-6 and VEGF but reduced IL-1β production. Except for the SoftMesh group, MSC coating significantly blunted release of all cytokines to levels even lower than with MΦs cultured alone. MΦs tended to deteriorate in the presence of MSCs. Both histology and TEM revealed intimate interactions between cell-coated meshes and MΦs.

CONCLUSIONS

Cytokine response to fibroblast coating varied, while MSC coating blunted the immunogenic effect of both synthetic and biologic meshes in vitro. Cell coating appears to affect mesh biocompatibility and may become a key process in mesh evolution.

Bioprosthetic tissue matrices in complex abdominal wall reconstruction

Background:

Complex abdominal defects are difficult problems encountered by surgeons in multiple specialties. Although current evidence supports the primary repair of these defects with mesh reinforcement, it is unclear which mesh is superior for any given clinical scenario. The purpose of this review was to explore the characteristics of and clinical relevance behind bioprosthetic tissue matrices in an effort to better clarify their role in abdominal wall reconstruction.

Methods:

We reviewed the peer-reviewed literature on the use of bioprosthetic mesh in human subjects. Basic science articles and large retrospective and prospective reviews were included in author’s analysis. The clinical performance and characteristics of 13 bioprosthetic tissue matrices were evaluated.

Results:

The majority of the products evaluated perform well in contaminated fields, where the risk of wound-healing difficulties is high. Clinical outcomes, which included infection, reherniation, and bulge formation, were variable, and the majority of the studies had a mean follow-up of less than 24 months.

Conclusions:

Although bioprosthetic matrix has a multitude of indications within the growing field of abdominal wall reconstruction, the functionality, regenerative capacity, and long-term fate of these products have yet to be fully established. Furthermore, the clinical performance, indications, and contraindications for each type of matrix need to be fully evaluated in long-term outcome studies.

Biological Matrices and Synthetic Meshes Used in Implant-based Breast Reconstruction - a Review of Products Available in Germany

While autologous breast reconstruction was considered the procedure of choice for immediate breast reconstruction, there has been a shift towards implant-based breast reconstruction (IBBR) in recent years. The proven safety of silicone breast implants and the development of biological matrices and synthetic meshes have contributed to the growing popularity of this approach. Although these different products are widely used, only limited clinical data are available with regard to breast surgery. The aim of this review was to give an overview of available biological matrices and synthetic meshes and discuss their use in clinical practice.

Postimplantation host tissue response and biodegradation of biologic versus polymer meshes implanted in an intraperitoneal position

BACKGROUND

This study compared the in vitro and in vivo behaviors at the peritoneal interface of a new polymer material (Bio-A) and of two biologic non-cross-linked materials (Tutomesh [Tuto] and Strattice [St]), all biodegradable.

METHODS

Omentum mesothelial cells from rabbits were seeded onto the three prosthetic materials tested. At 1, 4, 8, 16, and 24 h after implantation, mesothelial cover was performed using a scanning electron microscope (SEM). In the in vivo study, 3 × 3 cm mesh fragments were placed on the parietal peritoneum of the same rabbits and fixed at the four corners with individual stitches. The implants were randomized such that six fragments of each material were implanted in nine animals (2 per animal). Adhesion formation was quantified by sequential laparoscopy and image analysis 3, 7, and 14 days after implantation. The animals were killed at 90 days, and the meshes were subjected to microscopy and immunohistochemistry.

RESULTS

The in vitro mesothelial cover was significantly greater for St than for Bio-A at each time point. The percentage of cover for St was also higher than for Tuto 16 and 24 h after seeding and higher for Tuto than for Bio-A at all time points. Compared with the biologic meshes, significantly higher adhesion percentages were recorded for Bio-A. At 90 days after implantation, differences in absorption measured as percentage of reduction in mesh thickness were detected among all the meshes. The least absorbed was St. The neoperitoneum thickness was significantly greater for the biologic meshes than for the polymer mesh, although this variable also differed significantly between St and Tuto. Macrophage counts were higher for Bio-A than for the biologic meshes.

CONCLUSIONS

Greater mesothelial cover was observed in vitro for St. In vivo, adhesion formation and the macrophage response induced by Bio-A were greater than those elicited by the biologic materials. Bio-A and Tuto showed substantial biodegradation compared with St.

Biology of biological meshes used in hernia repair

Successful repair of most hernias requires the use of a prosthetic implant for reinforcement of the defect. Because of the need for prosthetic implants to resist infections as well to support repairs in contaminated or potentially contaminated fields, biological meshes have been developed to take the place of nondegradable synthetic meshes in cases where mesh infection is of high concern. The ideal is a biological matrix that resists infection while providing durable reinforcement of a hernia repair. This article reviews the validity of assumptions that support the purported notion of the biological behavior of biological meshes.

Efficacy of acellular dermal matrices in revisionary aesthetic breast surgery: a 6-year experience

BACKGROUND

Augmentation mammaplasty and augmentation mastopexy are associated with a substantial primary and secondary revision rate. Capsular contracture (CC), implant malposition, ptosis, asymmetry, and rippling are the main reasons for revisionary surgery in these patients. Traditional corrective techniques have not been completely reliable in preventing or treating these complications. Recently, acellular dermal matrices (ADM) have been used to assist with revisionary surgery with promising results.

OBJECTIVE

The authors review their 6-year experience using ADM for revisionary surgery in aesthetic patients and evaluate long-term outcomes with this approach.

METHODS

Patients who underwent revisionary breast augmentation or augmentation mastopexy with ADM in conjunction with standard techniques over a 6-year period between October 2005 and December 2011 were retrospectively reviewed. Only patients with at least 1 year of follow-up were included in the analysis.

RESULTS

A total of 197 revisions were performed (197 patients). Reasons for revision included CC (61.8%), implant malposition (31.2%), rippling (4.8%), ptosis (4.8%), implant exposure (1.6%), and breast wound (0.5%). The mean ± SD follow-up period was 3.1 ± 1.1 years (range, 0.1-6.1 years). The complication rate was 4.8%, including Baker grade III/IV CC (1.6%), infection (1.6%), implant malposition (0.5%), hematoma (0.5%), and seroma (0.5%). Most (98%) revisions were successful, with no recurrence of the presenting complaint.

CONCLUSIONS

The use of ADM in conjunction with standard techniques for the reinforcement of weak tissue in revision augmentation and augmentation mastopexy patients appears to be effective.

Repair of abdominal wall defects with biodegradable laminar prostheses: polymeric or biological?

Introduction

Biological and synthetic laminar absorbable prostheses are available for the repair of hernia defects in the abdominal wall. They share the important feature of being gradually degraded in the host, resulting in place the formation of a neotissue. This study was designed to assess the host tissue’s incorporation of collagen bioprostheses and a synthetic absorbable prosthesis.

Methods

Partial defects were created in the abdominal walls of 72 New Zealand rabbits and repaired using collagen bioprostheses Tutomesh® and Strattice® or a synthetic prosthesis Bio-A®. Specimens were collected for light microscopy, collagens gene and protein expression, macrophage response and biomechanical resistance at 14, 30, 90 and 180 days post-implantation.

Results

Tutomesh® and Bio-A® were gradually infiltrated by the host tissue and almost completely degraded by 180 days post-implantation. In contrast, Strattice® exhibited material encapsulation, no prosthetic degradation and low cell infiltration at earlier timepoints, whereas at later study time, collagen deposition could be observed within the mesh. In the short term, Bio-A® exhibited higher level of collagen 1 and 3 mRNA expression compared with the two other biological prostheses, which exhibited two peaks of higher expression at 14 and 90 days. The expression of collagen III was homogeneous throughout the study and collagen I deposition was more evident in Strattice®. Macrophage response decreased over time in biomeshes. However, in the synthetic mesh remained high and homogeneous until 90 days. The biomechanical analysis demonstrated the progressively increasing tensile strength of all biomaterials.

Conclusions

The tissue infiltration of laminar absorbable prostheses is affected by the structure and composition of the mesh. The synthetic prosthesis exhibited a distinct pattern of tissue incorporation and a greater macrophage response than did the biological prostheses. Of all of the laminar, absorbable biomaterials that were tested in this study, Strattice® demonstrated the optimal levels of integration and degradation.